626d55b9a8
The UTXO set has grown significantly, and flushing it from memory to LevelDB often takes over 20 minutes after a successful IBD with large dbcache values. The final UTXO set is written to disk in batches, which LevelDB sorts into SST files. By increasing the default batch size, we can reduce overhead from repeated compaction cycles, minimize constant overhead per batch, and achieve more sequential writes. Experiments with different batch sizes (loaded via assumeutxo at block 840k, then measuring final flush time) show that 64 MiB batches significantly reduce flush time without notably increasing memory usage: | dbbatchsize | flush_sum (ms) | |-------------|----------------| | 8 MiB | ~240,000 | | 16 MiB | ~220,000 | | 32 MiB | ~200,000 | | *64 MiB* | *~150,000* | | 128 MiB | ~156,000 | | 256 MiB | ~166,000 | | 512 MiB | ~186,000 | | 1 GiB | ~186,000 | Checking the impact of a `-reindex-chainstate` with `-stopatheight=878000` and `-dbcache=30000` gives: 16 << 20 ``` 2025-01-12T07:31:05Z Flushed fee estimates to fee_estimates.dat. 2025-01-12T07:31:05Z [warning] Flushing large (26 GiB) UTXO set to disk, it may take several minutes 2025-01-12T07:53:51Z Shutdown: done ``` Flush time: 22 minutes and 46 seconds 64 >> 20 ``` 2025-01-12T18:30:00Z Flushed fee estimates to fee_estimates.dat. 2025-01-12T18:30:00Z [warning] Flushing large (26 GiB) UTXO set to disk, it may take several minutes 2025-01-12T18:44:43Z Shutdown: done ``` Flush time: ~14 minutes 43 seconds.
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
What is Bitcoin Core?
Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.
Further information about Bitcoin Core is available in the doc folder.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/licenses/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled during the generation of the build system) with: ctest. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: build/test/functional/test_runner.py
(assuming build is your build directory).
The CI (Continuous Integration) systems make sure that every pull request is built for Windows, Linux, and macOS, and that unit/sanity tests are run automatically.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.